The present invention relates to a connection device intended for an array of electronic-card-holding modular structures. These modular structures are known by the name LRM standing for Line Replaceable Module.
Such a modular structure comprises a case containing one or more electronic cards and is provided with at least one connection block, which has to cooperate with the connection device, in order to provide a link between the electronic cards and an external installation with which a flow of signals can be established. The term xe2x80x9celectronic cardxe2x80x9d encompasses all substrates on which electronic components such as printed circuits may be interconnected, ceramic substrates, silicon substrates, etc. The modular structures of the array are usually grouped together in a rack.
The external installation may, but not exclusively, be located on board an aircraft. In this application, signals pass between one or more racks and the various components of the aircraft, such as, for example, the flaps, the control surfaces, the landing gear, the navigation instruments, various pressure and temperature sensors, etc.
These signals are not exclusively electrical signalsxe2x80x94they may be optical signals for example. In the modular structures, the signals are processed by the electronic cards. A communication is thus established between electronic cards of the same modular structure or of various modular structures.
In modern aircraft, the components capable of delivering or receiving such signals are extremely numerous and, in addition, the concept of integrated modular avionics, which is tending to replace distributed electronic functions by centralized racks, has a concentrating effect on the signals. Consequently, it is possible for several thousands of conductors conveying these signals to arrive close to the modular structures located in the rack.
The problems encountered are therefore numerousxe2x80x94they occur especially at the moment of connecting the conductors to the modular structures but also when carrying out troubleshooting work.
FIG. 1 shows diagrammatically, in exploded view, a connection device for an array E of modular structures of known type. The modular structures 1 are to be slid into the rack 2 in the manner of a drawer. Conventionally, the modular structures 1 are in the form of a casing housing one or more electronic cards (not visible in FIG. 1). Their front face 11 generally has a locking handle 12 (shown schematically) serving for inserting and removing the modular structure 1. Their rear face 13 has one or more multipoint connection blocks 14 connected to the electronic cards. The presence of such connection blocks in FIG. 1 can be imagined.
The connection device occupies the back 3 of the rack 2 and is protected by a cover 31 which is fixed to the rack 2. The connection device comprises at least one so-called backplane circuit 32, which is printed or flexible, provided with connection blocks 33 which project toward the connection blocks 14 on the modular structures 1 when the circuit is in place. These connection blocks 33 are intended to be coupled to those of the modular structures 1.
Bundles of conductors 4 arrive at the front face of the rack 2, they come from the various components of the external installation I shown schematically by a dotted rectangle. These conductors 4 terminate in one or more connection blocks 5.1 which are connected, from the front face of the rack 2, to other connection blocks 5.2. The combination of conductors 4 and connection blocks 5.1, 5.2 take up a large amount of space that cannot be used by the electronics. Between these connection blocks 5.1, 5.2 and the connection blocks 33 there is a very dense network of first conductors 60 which provide a link with the backplane circuit 32.
The backplane circuit 32 accommodates, in addition, second conductors 61 which connect the connection blocks 33 together, when signals have to pass between electronic boards belonging to various modular structures 1.
This type of connection architecture is not easy to design since the density of the conductors 4, 61, 60 is high. In FIG. 1, the thousands of conductors cannot be shown. Between the connectors 5.1, 5.2 and the backplane circuit 32, the first conductors 60 form a bottleneck difficult to implement. Should there be a fault, this is not easy to locate and repair.
The backplane circuit 32 is specific to the rack 2 and another arrangement of modular structures 1 in the rack 2 cannot be envisioned without changing the backplane circuit 32. In addition, the bundles of conductors 4 may constitute an impediment during their return to the external installation I, by running along the side, the top or the underside of the rack 2, while very often this place could be used to affix other racks 2.
The objective of the present invention is especially to solve these connection, maintenance and space-constraint problems.
To achieve this objective, the connection device according to the invention comprises, near the array of modular structures:
a plate provided with openings,
terminal connection blocks coming from the external installation, having to be inserted into the openings and each having to be coupled directly to a connection block carried by one of the modular structures and,
fastened to the plate, a circuit for distributing signals between modular structures, which is protected from the ambient environment.
The protection from the ambient environment may be accomplished by a cap which covers at least the signal distribution circuit when it is placed between the plate and the cap.
The signal distribution circuit may be immobilized between the plate and the cap by at least one first spacer and at least one second spacer, respectively.
The signal distribution circuit may include at least one conducting termination cooperating with a first-type connection block which has to be directly coupled to a connection block carried by a modular structure of the array, this first-type connection block having to be inserted into an opening in the plate.
When communication with at least one modular structure external to the array is required, the signal distribution circuit includes at least one conducting termination cooperating with a second-type connection block leading to the modular structure external to the array.
The second-type connection block can be inserted into an opening in the cap.
The cap may be made of metal or be metallized in order to protect against electromagnetic interference of the signal distribution circuit.
The terminal connection blocks can be fastened to the plate in order to ensure reliability of the electrical and mechanical connections and to contribute to electrical ground continuity.
Similarly, the second-type connection block can be fastenable to the cap.
To avoid connection errors during fitting, it is preferable for the openings in the plate and the terminal connection blocks to be provided with polarization means.
Above all, if the second-type connection block is similar to the terminal connection blocks, it is preferable for the opening in the cap and the second-type connection block to be provided with polarization means.
The present invention also relates to a rack intended to contain an array of electronic-card-carrying modular structures which is intended to cooperate with a connection device according to the invention. This rack possesses faces among which one that serves as the back, the back housing the plate of the connection device.
To be able to assemble several racks without being impeded by protruding assembly means, at least one of the faces of the rack has at least one recessed external assembly region, this region having to accommodate the assembly means which remain set back or flush with the face after the assembly operation.
One or more of its faces are provided with at least one orifice for cooling the modular structures.
If a large number of modular structures has to be accommodated by it, it is preferable that it contain at least one stiffening partition defining at least two housings for the modular structures (1).